proc: remove Alexey from MAINTAINERS

People Cc me and I don't have time.

Link: https://lkml.kernel.org/r/YKarMxHJBIhMHQIh@localhost.localdomain


Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>